Cooling tower method and apparatus

ABSTRACT

A cross-flow cooling tower having a frame assembly that is unitarily molded from a plastic material. The frame assembly has opposing top and bottom walls along with opposing side walls and opposing ends. The side walls extend parallel to one another between the top and bottom walls. In addition, the opposing ends extend parallel to one another between the top and bottom walls. The frame assembly additionally has a vertical stack extending vertically from the top wall. The top covers of the tower extend outwardly and downwardly from the vertical stack.

PRIORITY

[0001] This application claims priority to the provisional U.S. patentapplication entitled, COOLING TOWER METHOD AND APPARATUS, filed Nov. 2,2001, having a serial No. 60/330,896, the disclosure of which is herebyincorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to a method and apparatusfor the disposal of heat utilizing a heat exchange liquid. Moreparticularly, the present invention relates to a method and apparatusfor a cross-flow water cooling tower wherein the water cooling tower isemployed, for example, to dispose of large quantities of heat generatedby various industrial processes.

BACKGROUND OF THE INVENTION

[0003] Cooling towers are used in many applications. For example, airconditioning systems for large buildings employ cooling towers forcarrying out a portion of the heat exchange that is essential to thecooling process. Industrial processes, such as chemical production,metals production, plastics production, food processing, etc., generateheat that must be disposed of, often by the use of cooling towers. Thecooling tower is a housing that channelizes air in proximity to a heatexchange liquid, for example, water. A heat exchange fluid may becirculated through the cooling tower and at least one fan may be mountedon the cooling tower to produce a flow of cooling air in proximity tothe heat exchange liquid. Heat is transferred from the heat exchangefluid to the air, largely through the evaporation of a small percentageof fluid which substantially lowers the temperature of the primary heatexchange fluid. The cooled heat exchange fluid can then return to theindustrial process to perform a heat exchange function for eitherindustrial processes or commercial air conditioning systems.

[0004] Conventional cross-flow cooling towers are presently inwidespread use in such areas as factory complexes, chemical processingplants, hospitals, apartment and/or condominium complexes, warehousesand electric generating stations. Conventional cross-flow cooling towersare constructed with upright unitary or sectionalized fill structuressurmounted by hot water distribution basins and cold water collectionbasins. The hot water basins are usually equipped with target nozzles orother hot water distributors which distribute the incoming water overthe fill. The interior space bounded by the fill structures and the coldwater basins define the plenum for the tower. A fan assembly made up ofan apertured horizontal deck, which supports an upright, venturi-shapedstack, is positioned at the upper opening of the water cooling tower.This configuration provides a plenum large enough to enable a smoothtransition of the flow gas from the generally horizontal direction,through the fill assembly, to the generally vertical direction, and outthe exhaust port of the tower assembly. In the operation of thecross-flow cooling towers, hot water is introduced at the top of thefill while the air is introduced along the upright sides of the tower.As the water descends in an even distribution along the fill section,the cooling cross-flow air currents intersect the descending water in aheat exchanging relation. Subsequently, the cooled water is collected ina water basin below while the hot, moist air is discharged into theatmosphere.

[0005] In a cross-flow cooling tower, there is no necessity for the airto make radical changes of direction into the fill and the air inlet isspaced along the entire height of the fill. Therefore, the overall airpressure losses in the fill are usually less than those of aconventional counter-flow tower resulting in the passing of air throughthe tower more easily.

[0006] Conventional cross-flow cooling towers generally employ variousvarieties of splash-type fill sections consisting of elongated bars of aspecific configuration for dispersing the descending released water.More recently, film type fill sections have been developed which haveproven substantially more efficient than splash fill sections. Thesetypically corrugated film fills generally consist of a series of thin,opposed sheets formed of synthetic resin materials in which water passesalong the sheets of “film”.

[0007] The highest potential for cooling exists at the top of the airinlet sides where the hottest water comes into contact with the coldestair. Once such air has been heated such that the wet bulb temperature ofthe air is near the water temperature, the air has no more capacity tocool the water, and such heat saturated air prevents the introduction ofcooler ambient air into the fill. Air near the top of the towertypically experiences this condition because it initially contacts thehottest water, and all other water along its path of travel is about thesame temperature. Air entering near the bottom of the tower initially isexposed to water that has been significantly cooled. As it traversesthrough the fill, the temperature of the water encountered by the bottomair currents rises, which allows the air to take on more heat.

[0008] The hot water basins in a cross-flow tower are normallyconstructed to serve as an air seal to prevent air entering the towerthrough the top of the fill. Additionally, air seals along the length ofthe tower are provided along the inboard and outboard edges of thebasins to seal from the bottom of the basins to the top of the fill.These seals prevent air from entering the spray chamber and bypassingthe fill structure. Sealing of the distribution basins also minimizesthe contact between incoming air currents and relatively large waterparticles adjacent the spray nozzles or water distributors.

[0009] Presently, a majority of unitary cooling towers are assembledfrom a plurality of pieces of sheet metal that are mounted to a metallicsupport frame. Unitary cooling towers typically are manufactured at alocation remote from the installation site. The towers are then shippedto the installation site in a substantially assembled form. Due to themetallic materials with which the cooling towers are assembled, thetowers are fairly heavy and therefore require extensive structuralsupport. In addition, the cost of present cooling towers are alsoadversely affected by the labor intensive processes for manufacturingand assembling the various metallic components of the cooling towers.

[0010] Metallic cooling towers are also subject to corrosion and/orrust. Thus, the metallic towers have a relatively short operationallife. Corrosion and/or rust problems can be deterred by employingcorrosion and/or rust resistant alloys. However, these metallicmaterials significantly increase the manufacturing cost of the watercooling tower. Alternatively, plastics such as polyethylene are wellknown for being moldable into prescribed form and function and areutilized in the art. However, polyethylene material properties arerelatively weak and flexible. To compensate for these properties inmonolithic parts, designers must use large quantities of polyethylene tocreate bigger, thicker and deeper sections to minimize stresses anddeflections.

[0011] Accordingly, it is desirable to provide a cooling tower designthat offers a substantial reduction in parts, avoiding complex andcostly assembly of components. It is also desirable to manufacture awater cooling tower that is light in weight, durable and resistscorrosion.

SUMMARY OF THE INVENTION

[0012] The foregoing needs are met, to a great extent, by the presentinvention where, in one aspect, a cross-flow cooling tower is providedhaving a frame assembly that is unitarily molded from a plasticmaterial. The frame assembly has opposed top and bottom walls that areparallel to one another along with opposed, parallel side walls thatextend between the top and bottom walls. The frame assembly also hasopposed, parallel ends that similarly extend between the top and bottomwalls. The cross-flow cooling tower additionally has a vertical stackthat extends vertically from the top wall. The top covers of thecross-flow cooling tower project outwardly and downwardly from thevertical stack, contacting the side walls and the opposing ends of thewater cooling tower.

[0013] In accordance with another aspect of the present invention, aframe assembly is provided having a shell unitarily molded from plasticmaterial. The unitary shell includes opposed parallel top and bottomwalls along with opposed parallel end walls. The aforementioned sidewalls and ends both extend between the top and bottom walls.

[0014] In accordance with yet another aspect of the present invention, atop for a cooling tower is provided having a hot liquid inlet and agenerally planar bottom with at least one opening therein foraccommodating an air current generator. In addition, the planar bottomhas a plurality of hot liquid distributors oriented to distribute hotliquid. The cooling tower top additionally has opposed parallel sidewalls unitarily connected to the bottom wall. In addition, the coolingtower top has opposed, parallel end walls connected to the bottom wall.The aforementioned side and end walls are unitarily connected to a topwall wherein the top wall has at least one opening formed therein foraccommodating an air current generator. The top wall projects outwardlyand downwardly from the opening.

[0015] There has thus been outlined, rather broadly, the more importantfeatures of the invention in order that the detailed description thereofthat follows may be better understood, and in order that the presentcontribution to the art may be better appreciated. There are, of course,additional features of the invention that will be described below andwhich will form the subject matter of the claims appended hereto.

[0016] In this respect, before explaining at least one embodiment of theinvention in detail, it is to be understood that the invention is notlimited in its application to the details of construction and to thearrangements of the components set forth in the following description orillustrated in the drawings. The invention is capable of otherembodiments and of being practiced and carried out in various ways.Also, it is to be understood that the phraseology and terminologyemployed herein, as well as the abstract, are for the purpose ofdescription and should not be regarded as limiting.

[0017] As such, those skilled in the art will appreciate that theconception upon which this disclosure is based may readily be utilizedas a basis for the designing of other structures, methods and systemsfor carrying out the several purposes of the present invention. It isimportant, therefore, that the claims be regarded as including suchequivalent constructions insofar as they do not depart from the spiritand scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a perspective view of a cross-flow cooling tower inaccordance with a first embodiment of the present invention.

[0019]FIG. 2 is a perspective view of a rotationally molded unitaryframe assembly of the first embodiment of the present invention withtower covers unitarily attached to the opposing frame ends.

[0020]FIG. 3 is a top view of a top tower cover in accordance with thefirst embodiment of the present invention after the cover has beendetached from an opposing end of the unitary frame assembly illustratedin FIG. 2.

[0021]FIG. 4 is a perspective view of the rotationally molded unitaryframe assembly of the first embodiment of the present invention with thetower covers removed from the frame ends revealing the air intake portsof the frame assembly.

[0022]FIG. 5 is a perspective view of a cross-flow cooling tower inaccordance with the first embodiment of the present invention with therotationally molded unitary frame assembly shown in phantom.

[0023]FIG. 6 is a side cross-sectional view of a cross-flow coolingtower according to the first embodiment employing a rotationally molded,unitary frame assembly with top covers.

[0024]FIG. 7 is a perspective view of a second embodiment of across-flow cooling tower in accordance with the present invention.

[0025]FIG. 8 is a perspective view of a hot water distribution unit inaccordance with the second embodiment of present invention.

[0026]FIG. 9 is a partial, cutaway view of the hot water distributionunit in accordance with the second embodiment of the present inventionand showing a distribution pan or tray contained therein.

[0027]FIG. 10 is a perspective view of the underside of the hot waterdistribution unit of FIG. 9 in accordance with the second embodiment ofthe present invention.

[0028]FIG. 11 is a perspective view of an alternative two-piece hotwater distribution unit in accordance with the second embodiment presentinvention.

[0029]FIG. 12 is a top view of a cold water collection basin inaccordance with the second embodiment of present invention.

[0030]FIG. 13 is a perspective view a flow splitter employed in apreferred embodiment of the present invention.

[0031]FIG. 14 is a perspective view of a flow splitter employed in apreferred embodiment of the present invention.

[0032]FIG. 15 is a perspective view of two liquid collection basins thatare molded together as one entity and then separated in accordance withan alternative embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0033] Referring now to the figures wherein like reference numeralsindicate like elements, FIGS. 1-15 illustrate the presently preferredembodiments of a cross-flow cooling tower. While in the embodimentdepicted the tower is a water cooling tower, it should be understoodthat the present invention is not limited in its application to watercooling towers, and can be used for other types of cooling towers.

[0034] Referring now to the first embodiment illustrated in FIGS. 1-6, across-flow cooling tower, generally designated 10, is illustrated forcontacting generally horizontally flowing gas in a cooling relationshipwith generally vertically descending liquid. As seen in FIG. 4, thecooling tower includes a frame assembly 12 that is unitarily molded frompolyethylene in a rotational mold, illustrated in FIG. 2, having a top14, a bottom 16, two opposed side walls 18 and two opposed ends 20. Moreparticularly, as seen in FIGS. 1-6, the tower is made up of a unitarilymolded polyethylene frame assembly 12 reinforced by a mill galvanizedsteel skeleton 24, two upright fill assemblies 26, a hot waterdistributor 28 located above the fill assemblies 26, a vertical stack 30extending upwardly from the hot water distributor 28, a cold watercollection basin 32 below the fill assemblies 26, air intake ports 36,an exhaust port 39 and a cooling air current generator employing a fanunit 37. Skeleton 24 may be composed of other suitable materials such asstainless steel, hot dipped galvanized steel, epoxy coated steel, FRP(fiber reinforced plastic), etc. Fill assemblies 26 extend across theentire faces of air intake ports 36. Only a few fill sheets are shown inassemblies 26 to add clarity to the structural features of tower 10.

[0035] After removal of the covers 34, the unitary frame assembly 12includes two opposed side walls 18 that extend parallel to one anotherand are unitarily connected to a bottom generally planar wall and a topplanar wall. The side walls 18 intersect the top generally planar wallto form the sides of the hot water distributor 28 above the fillassemblies 26 and intersect the bottom generally planar wall to form theside walls of the cold water collection basin 32 below the fillassemblies 26. As can be observed in FIG. 2, the opposed ends 20 of theframe assembly 12 intersect both the top and bottom generally planarwalls of the cooling tower, forming the end barriers to the hot waterdistributor 28 and the cold water collection basin 32 respectively.

[0036] As illustrated in FIG. 2, initially, the unitarily polyethyleneframe 12 is rotationally molded having solid opposing ends 20 whereinthe cooling tower covers 34 are molded to be included within theopposing ends 20. Upon completion of the molding process, the solidopposing ends 20 and the tower covers 34 connected therein, are removedfrom the unitary frame 12 by a cutting means. The tower covers 34 arethen prepared for installation and assembly above the hot waterdistributor 28. As a result of the removal of the tower covers 34, theopposing ends 20 of the cooling tower are designated air intake ports 36when the tower is in operation. The aforementioned rotational molding ofthe unitary frame body 12 and following removal of the tower covers 34offers a cost effective way for manufacturing and assembling across-flow water cooling tower by limiting the waste of manufacturingmaterials and by substantially reducing the amount of parts and assemblyrequired.

[0037] In lieu of molding the tower covers 34 in opposed ends 20,louvers to prevent splash out of water may be molded into this face. Airinlet openings may be fabricated by removing the material around theintended louver structure. Molding the louvers in this face negates therequirement for attaching separate louvers or providing fill withintegral louvers.

[0038] As illustrated in FIG. 4, the unitarily molded frame assembly 12includes a hot water distributor 28 with a vertical stack 30 extendingvertically therefrom and a cold water collection basin 32 disposed belowthe distributor. The frame 12 additionally includes two opposing sidewalls 18 that extend parallel to one another between the collectionbasin 32 and hot water distributor 28. The assembly also has twoopposing intake ports 36.

[0039] The hot water distributor 28 contains a distribution pan or tray38 positioned directly above the fill assemblies that permits water togravitate through a plurality of apertures, perforations and/or nozzles41 onto the top surfaces of the upper film sections of the fillassemblies 26. The water is supplied to the distribution pan or tray byway of supply pipe (not shown) and enters the assembly via the waterinlet 40 shown in FIG. 1. Water is delivered to hot water distributor 28and is distributed evenly to both sides with the aid of a generallyinverted “V” shaped flow splitter 90 as illustrated in FIGS. 13 and 14.Flow control devices or valves are not required to balance the flow.Flow splitter 90 divides the flow and provides a barrier to preventtransitory or oscillatory flow variation from side to side.

[0040] The cold water collection basin 32 is disposed below the fillassemblies 26 in a position to receive liquid gravitating therefrom. Thebasin extends across the entire width of the cooling tower 10 and may becoupled to a pumping structure (not shown) suitable for removingdeposited liquid therein and for delivering the water to equipmentrequiring the same for cooling and/or returning the water to the supplysource.

[0041] Referring now to FIG. 5, the polyethylene frame of the coolingtower 10 and components contained therein, are supported by conventionalmill galvanized steel framework 24 as shown. The framework 24 offerssupport and strength to the tower frame while making the tower moredurable, extending the cooling tower's operational life.

[0042] Polyethylene is a well-known plastic material used substantiallyfor liquid containers such as milk jugs, and gallon gasoline containers.Polyethylene is a relatively inexpensive plastic and is dependable forcontaining liquids at low-pressure. However, polyethylene has relativelylow material mechanical properties. The modulus of elasticity is onlyabout 80,000 psi to 100,000 psi. By contrast the modulus of elasticityof steel is 29,000,000 psi which is about 300 times that ofpolyethylene. The implications for deflections are huge. For simplebeams of the same geometry and loading, the one made of polyethylenewill deflect 300 times the deflection of the steel beam. Therefore, tolimit the deflections of polyethylene structures, the unsupported spansmust be reduced very substantially and/or the cross-section increasedvery substantially compared to steel structures.

[0043] For example a simply supported beam subjected to a uniform loadexperiences a maximum deflection, Δ, according to following equation:

Δ=5w L ⁴/(384 EI)  (1)

[0044] in which

[0045] w≡uniform load per unit length

[0046] L≡length of simple span

[0047] E≡modulus of elasticity

[0048] I≡moment of inertia of the beam cross-section

[0049] To maintain the same deflection for a given span, L, and givenuniform load, w, the product of EI for each beam must be constant:

E_(p)I_(p)=E_(s)I_(s)   (2)

[0050] in which subscripts p and s are polyethylene and steelrespectively. Solving for the required polyethylene moment of inertiagives the following equation:

I _(p) =I _(s) E _(s) /E _(p)   (3)

[0051] Taking the modulus of elasticity as 29,000,000 psi for steel and100,000 psi for polyethylene, the required polyethylene beam moment ofinertia is

I _(p) =I _(s)(29,000,000/100,000)=290 I _(s)   (4)

[0052] For a simple rectangular beam cross-section the moment of inertiais computed as follows:

I=bh ³/12   (5)

[0053] in which

[0054] b=beam width

[0055] h=beam height

[0056] Assuming a constant proportion of the width, b, to the height, h,the moment of inertia can be rewritten as:

I=αh ⁴/12   (6)

[0057] in which

[0058] α≡b/h or b=αh

[0059] Substituting equation 6 with respective subscripts for steel andpolyethylene in equation 4 and solving for the height of thepolyethylene beam cross-section gives the following equation:$\begin{matrix}\begin{matrix}{h_{p} = \left( {290\quad h_{s}^{4}} \right)^{0.25}} \\{= {4.13\quad h_{s}}}\end{matrix} & (7)\end{matrix}$

[0060] Therefore, the cross-section of the polyethylene beam must beover 4 times wider and over 4 times higher to carry the same load andmaintain the same deflection for a given span.

[0061] The cross-sectional area, A, for the rectangular cross-section is

A=bh   (8)

[0062] Substituting the proportionality constant expression, b=αh, fromequation 6 gives the equation

A=αh²   (9)

[0063] The cross-sectional area of the polyethylene beam, A_(p), is$\begin{matrix}\begin{matrix}{A_{p} = {\alpha \quad h_{p}^{2}}} \\{= {\alpha \quad \left( {4.13\quad h_{s}} \right)^{2}}} \\{= {17.1\quad \alpha \quad h_{s}^{2}}} \\{= {17.1\quad A_{s}}}\end{matrix} & (10)\end{matrix}$

[0064] Therefore, the cross-sectional area of the polyethylene beam isover 17 times that of the steel beam. The specific gravity of steel andpolyethylene relative to water are about 7.85 and 0.94 respectively.Steel weighs about 7.85/0.94=8.4 times as much as polyethylene for thesame volume of material.

[0065] The volume of the beam, V, is

V=AL   (11)

[0066] The volume of the polyethylene beam may be expressed in terms ofthe volume of the steel beam as follows: $\begin{matrix}\begin{matrix}{V_{p} = {A_{p}\quad L}} \\{= {17.1\quad A_{s}\quad L}} \\{= {17.1\quad V_{s}}}\end{matrix} & (12)\end{matrix}$

[0067] The weight of the beam is determined by multiplying the specificweight, γ, times the volume.

W_(s) =γ _(s) V _(s)   (13)

W_(p) =γ _(p) V _(p)   (14)

[0068] $\begin{matrix}\begin{matrix}{W_{p} = {\left( {\gamma_{p}/\gamma_{s}} \right)\quad \gamma_{s}\quad \left( {17.1\quad V_{s}} \right)}} \\{= {17.1\quad \left( {\gamma_{p}/\gamma_{s}} \right)\quad W_{s}}}\end{matrix} & (15)\end{matrix}$

[0069] The specific weight of steel, γ_(s), is 490 lb/cf, and thespecific weight of polyethylene is about 59 lb/cf. Therefore, the weightof the polyethylene beam compared to the weight of the steel beam may beexpressed as follows: $\begin{matrix}\begin{matrix}{W_{p} = {17.1\quad \left( {59/490} \right)\quad W_{s}}} \\{= {2.06\quad W_{s}}}\end{matrix} & (16)\end{matrix}$

[0070] Therefore, the polyethylene beam is actually more than twice theweight of the steel beam.

[0071] Furthermore, rotationally molded polyethylene costs more per unitweight than does fabricated heavy mill galvanized (HMG) steel per unitweight. Thus, it is not economical to directly replace an HMG steel beamwith a polyethylene beam as it would cost more than twice as much.

[0072] The yield strength of polyethylene ranges from about 1300 psi to2800 psi. The yield strength of steel is about 36,000 psi, which isabout 28 to 13 times the strength of polyethylene. However, polyethyleneis a viscoelastic material which creeps (or moves) under sustained load.Long term sustained stress levels must be kept low to prevent thisviscoelastic behavior from causing unacceptable deflections over time.Steel does not creep and is not subject to this limitation.

[0073] Taking the beam example above for constant deflections, themaximum bending stress, f_(b), may be computed from the followingequation:

f _(b) =M/S   (17)

[0074] in which

M≡bending moment=wL ²/8   (18)

S≡section modulus=bh ²/6=αh ³/6   (19)

[0075] The section modulus of the polyethylene beam may be expressed interms of the section modulus of the steel beam as follows:$\begin{matrix}{S_{p} = {\alpha \quad {h_{p}^{3}/6}}} \\{= {\alpha \quad {\left( {4.13\quad h_{s}} \right)^{3}/6}}} \\{= {70.4\quad \left( {\alpha \quad {h_{s}^{3}/6}} \right)}} \\{= {70.4\quad S_{s}}}\end{matrix}$

[0076] Therefore, since the bending moment is assumed constant for theexample, the maximum bending stress in the polyethylene beam may beexpressed in terms of the maximum bending stress of the steel beam asfollows: $\begin{matrix}{f_{bp} = {M/S_{p}}} \\{= {M/\left( {70.4\quad S_{s}} \right)}} \\{= {f_{s}/70.4}}\end{matrix}$

[0077] Steel members are often sized for a maximum stress of about 0.6of the yield strength which is 0.6 (36,000 psi)=21,600 psi. Thepolyethylene maximum bending stress would be 21,600 psi/70.4=307 psi.This is about 0.1 to 0.2 times the yield strength of the polyethylene,which normally is sufficient to control creep.

[0078] The structural comparisons above show that polyethylene is noteconomical for structural applications. On the other hand steel is verywell suited for structural applications and has been used in a widevariety of applications including unitary cooling towers. Polyethyleneis corrosion resistant and formable by rotational molding into multiplefunctional shapes. The two materials compliment one another in astructural hybrid cooling tower design to produce a cost effective,durable product. A steel skeleton provides load paths to support thepolyethylene components.

[0079] As illustrated in FIG. 6, the fill assemblies 26 of the toweremploy up to a total of two film type fill packs or units which arealigned in a duplicate fashion in two opposed units so as to present adouble-flow tower. Each of the units is made up of a plurality ofupright, spaced apart film fill sheets of chevron or herringbone design.The film fill sheets are integrally constructed to include both louversand eliminators, which for example, may be the type illustrated in U.S.Pat. No. 4,548,766. Each of the units and thus the overall fillassemblies 26, present upright air inlet faces 42, opposed, upright airoutlet faces 44, and a generally horizontal upper face 46 extendingbetween the inlet face 42 and the outlet face 44. Therefore as a resultof the individual fill assembly orientation, the gas inlet 42 and outlet44 openings enable the flow of gas over substantially the entirevertical height of the fill assembly into the central plenum chamber 48of the water cooling tower 10.

[0080] Alternatively, the air inlet 42 faces may be provided withstationary louvers 50 utilized to prevent water from splashing out ofthe tower. Again, these louvers may be rotationally molded in opposedends 20 in lieu of basin covers 34. A drift eliminator wall 52 can bedisposed across the air outlet faces 44 and in generally an uprightposition to prevent entrained droplets of water from entering the plenumchamber 48 as spray. The wall may be of any type for example, ahoney-comb type eliminator or a series of spaced inclined baffles thatpermit the free flow of air there through but prevent significantquantities of liquid droplets from escaping the fill assemblies 26. Anexemplary eliminator is disclosed in U.S. Pat. No. 4,514,202. The fillassemblies 26, in conjunction with their respective eliminator walls,combine to form the tower's central plenum 48.

[0081]FIG. 6 illustrates that a vertical stack 30 is disposed above thehot water basin 28 and extends upwardly from the central plenum chamber48 to define the exhaust port 39 of the cooling tower 10. The fan unit37 is positioned within the stack 30 and is supported by horizontalsupport members 54 wherein the fan unit 37 employs a blade assemblycoupled to a motor. Operation of the fan unit 37 causes currents of airto be drawn through the fill assemblies 26 and forces the currentsupwardly through the plenum chamber 48 into the vertical stack 30 fordischarge through the exhaust port 39.

[0082] A variety of alternative components and designs can be used inthe water cooling towers of the present invention. FIG. 7 illustrates asecond embodiment of the present invention wherein a cooling tower 56 isdisplayed having a steel frame assembly composed of mill galvanizedsteel, and having a top, a bottom, two opposed side walls, two opposedends. More particularly, the tower consists of two opposed millgalvanized cold-formed steel side walls 58 parallel to one another, twoupright fill assemblies 60, a self contained hot water distribution unit62 above the fill assemblies 60, a cold water collection basin 64 belowthe fill assemblies 60, air intake ports 63, an exhaust port 65 and acooling air current generator employing a fan unit 66.

[0083] Referring now to FIGS. 7-11, and in accordance with the presentinvention, the hot water distribution unit 62 is rotationally moldedfrom polyethylene in one operation to produce a single, self enclosedunit that includes a generally planar, distribution pan or tray 68having apertures, perforations and/or nozzles 69, four walls 70unitarily connected to tower covers 72, and an opening 74 for towerexhaust. The covers 72 project outwardly and downwardly from the opening74. More particularly, the distribution unit 62 is a self contained unithaving a water inlet 76, a first set of opposing side walls 70 parallelto one another and second set of opposing sides walls 70 parallel to oneanother. Both sets of walls 70 extend vertically from the pan or tray 68and intersect the tower covers 72 to form a unitary enclosure, employedfor the distribution of hot water having a fan shroud 78. Raisedportions 73 are designed to manage water delivered to distribution unit62. Most importantly raised portions 73 serve to transform the inletpiping flow discharge disturbances into a more quiescent channel flowwhich is then released into distribution pans or trays 68. Anothersignificant benefit of raised portions 73 is reduction in the amount ofwater inventory carried in distribution unit 62, which reduces theoperating weight. The distribution unit 62 may be attached to thegalvanized steel frame of the water cooling tower 56 by fastening meanssuch as screw, welding, bolt, solder, and/or bracket.

[0084] In addition, as illustrated in FIG. 11, should the tower besufficiently large such that a single piece distribution unit 62 wouldbe impractical to rotationally mold, the distribution unit 62 may berotationally molded as two or more individual pieces 67 that aresubsequently joined together to form a distribution unit 62.

[0085] Referring now to FIG. 12, the cold water collection basin 64 isdisposed below the fill assemblies 60 in a position to receive liquidgravitating therefrom. The cold water basin 64 is a rotationally molded,unitary piece having a generally planar bottom surfaces 80 and 81, afirst set of opposed side walls 82 extending parallel to one anotheraway from the bottom surfaces 80, 81 and a second set of opposed sidewalls 84 extending parallel to one another away from the bottom surfaces80, 81. The basin 64 extends across the entire width of the coolingtower and may be coupled to a pumping structure suitable for removingdeposited liquid therein and for delivering the water to equipmentrequiring the same for cooling and/or returning the water to the supplysource. The cold water basin 64 may be attached to the galvanized steelframe of the water cooling tower by fastening means such as screw,welding, bolt, solder, and/or bracket.

[0086] In addition, should the tower be sufficiently large such that asingle piece collection basin 64 would be impractical to rotationallymold, the cold water collection basin 64 may rotationally molded as twoor more pieces that are subsequently joined together to form acollection basin 64.

[0087] In accordance with an alternative embodiment of the presentinvention, the hot water distribution unit 62 and collection basin 64illustrated in FIGS. 7-11 may be rotationally molded together as oneentity and then separated as illustrated in FIG. 15. As illustrated inFIG. 15, two basins 92 and 94 respectively, are rotationally moldedsimultaneously in a single molding process. The basins 92 and 94 arethen separated by a cutting element. The basins are then incorporatedinto a water cooling tower assembly as previously described, whereinbasin 92 is employed as a hot water distribution element and basin 94 isemployed as a cold water collection basin.

[0088] The aforementioned molding process is advantageous because itallows for the creation of an enclosed mold which reduces the amount ofwaste produced during the molding process. If the basins were to bemolded separately, a temporary top would be required to be molded foreach piece so that the basin mold could be closed. The molded, temporarytop portion would then have to be cut away from the basin to open it upresulting in wasted material. This embodiment does not include basincovers, however the covers may be fabricated separately and added to thetower assembly.

[0089] The many features and advantages of the invention are apparentfrom the detailed specification, and thus, it is intended by theappended claims to cover all such features and advantages of theinvention which fall within the true spirits and scope of the invention.Further, since numerous modifications and variations will readily occurto those skilled in the art, it is not desired to limit the invention tothe exact construction and operation illustrated and described, andaccordingly, all suitable modifications and equivalents may be resortedto, falling within the scope of the invention.

What is claimed is:
 1. A cross-flow cooling tower comprising: a frameassembly unitarily molded from a plastic material wherein said frameassembly comprises opposed top and bottom walls, opposed side wallsextending between said top and bottom walls, opposed ends extendingbetween said top and bottom walls; a vertical stack forming an exhaustport and extending vertically from said top wall; and a top cover,molded from a plastic material.
 2. The cross-flow cooling toweraccording to claim 1, wherein said top cover projects outwardly anddownwardly from said vertical stack.
 3. The cross-flow cooling toweraccording to claim 1, wherein said top cover comprises two pieces. 4.The cross-flow cooling tower according to claim 1, wherein said sidewalls and said ends are unitarily connected to said top wall to form ahot liquid distributor having a plurality of spaced apart aperturesand/or nozzles oriented to deliver hot liquid to be cooled.
 5. Thecross-flow cooling tower according to claim 1, wherein said top covercomprises a liquid inlet.
 6. The cross-flow cooling tower according toclaim 4, further comprising at least one cooling air current generatorfor directing air through said exhaust port.
 7. The cross-flow coolingtower according to claim 1, wherein said top cover is attached to saidhot liquid distributor by a fastener.
 8. The cross-flow cooling toweraccording to claim 1, wherein said side walls and said opposed ends areconnected to said bottom wall to form a liquid collection basin disposedbelow said hot liquid distributor.
 9. The cross-flow cooling toweraccording to claim 1, further comprising a supplemental supportstructure that provides support to said frame assembly.
 10. Thecross-flow cooling tower according to claim 9, wherein said supplementalsupport structure comprises steel members.
 11. The cross-flow coolingtower according to claim 1, further comprising an upright fill structureincluding a plurality of fill elements and presenting an upright airinlet face, an opposed upright air outlet face, and an upper faceextending transversely between said inlet and outlet faces.
 12. Thecross-flow cooling tower according to claim 11, further comprising acooling air current generator operable to produce cooling air currentswhich enter said fill structure via said inlet face and exit said fillstructure both laterally via said outlet face and upwardly via saidupper face.
 13. The cross-flow cooling tower according to claim 11,further comprising a drift eliminator located adjacent to said uprightair outlet face of said fill structure.
 14. The cross-flow cooling towertop according to claim 4, further comprising a flow splitter thatdivides the flow of incoming liquid.
 15. The cross-flow cooling toweraccording to claim 14, wherein said flow splitter is shaped like aninverted “V”.
 16. A frame assembly for a cooling tower comprising: ashell unitarily molded from plastic material, wherein said shellcomprises opposed top and bottom walls, opposed side walls extendingbetween said top and bottom walls, and opposed end walls extendingbetween said top and bottom walls.
 17. The frame assembly according toclaim 16, where said top wall further comprises at least one openingformed therein for mounting an air current generator.
 18. The frameassembly according to claim 16, wherein said side walls are alignedsubstantially perpendicular to said top and bottom walls.
 19. The frameassembly according to claim 16, wherein said end walls are alignedsubstantially perpendicular to said top and bottom walls.
 20. The frameassembly according to claim 16, wherein said top, bottom, side and endwalls intersect to define an interior of said frame assembly.
 21. Theframe assembly according to claim 16, wherein said side walls and saidend walls are unitarily connected to said top wall to form a hot liquiddistributor, said distributor having a plurality of spaced apartapertures and/or nozzles oriented to deliver hot liquid to be cooled.22. The frame assembly according to claim 16, wherein said side wallsand said end walls are unitarily connected to said bottom wall to form aliquid collection basin disposed below said hot liquid distributor. 23.The frame assembly according to claim 16, wherein said end walls areremovable and are shaped as cooling tower covers.
 24. The frame assemblyaccording to claim l6, wherein at least a portion of said end walls areshaped as louvers.
 25. A cross-flow cooling tower comprising: a frameassembly unitarily molded from a plastic material wherein said frameassembly comprises opposed top and bottom walls, opposed side wallsextending between said top and bottom walls, opposed ends extendingbetween said top and bottom walls; a vertical stack forming an exhaustport and extending vertically from said top wall; and support membersthat provide support to said frame assembly.
 26. The cross-flow coolingtower according to claim 25, further comprising louvers that are formedin said opposed ends of said frame assembly.
 27. The cross-flow coolingtower according to claim 25, further comprising a top cover, molded froma plastic material.
 28. A method for assembling a cooling towercomprising the step of: unitarily molding a frame assembly from aplastic material wherein the frame assembly comprises opposed top andbottom walls, opposed side walls extending between the top and bottomwalls, and opposed end walls extending between the top and bottom walls,shaped as cooling tower covers.
 29. A method according to claim 28,further comprising the step of removing the end walls to form a pair ofcooling tower covers.
 30. A method according to claim 29, furthercomprising the step of the attaching the removed cooling tower covers tothe frame assembly over the top wall.
 31. The method of claim 29,wherein the cutting step uses a laser, a hot edge, abrasion, highpressure water and/or a sharp edge.
 32. The method of claim 27, whereinthe frame assembly further comprises a metal support structure.
 33. Themethod of claim 32, wherein the support structure comprises steelmembers.
 34. A method for assembling a cooling tower comprising the stepof: unitarily molding a frame assembly from a plastic material whereinthe frame assembly comprises opposed top and bottom walls, opposed sidewalls extending between the top and bottom walls, and opposed end wallsextending between the top and bottom walls, shaped as louvers.
 35. Across-flow cooling tower comprising: a frame assembly unitarily moldedfrom a plastic material wherein said frame assembly comprises opposedtop and bottom walls, opposed side walls extending between said top andbottom walls, opposed ends extending between said top and bottom walls;a vertical stack forming an exhaust port and extending vertically fromsaid top wall; and means for providing supplemental support to saidframe assembly.